So my cousin just informed me that on a bitcoin address tracker site it says that I have something like .017 btc in my wallet but when I sign into said wallet it's nowhere to be found could someone please explain to me how these btc addy trackers work and exactly what it is saying because If that's true then how do i retrieve my 212.00$ in lost bitcoin
I assume your cousin means blockchain explorer, when he says address tracker.
An example of a blockhain explorer is
https://blockchain.info .
There you can enter your BTC address and check the balance.